Immunotherapy of murine transitional cell carcinoma of the bladder using alpha and gamma interferon in combination with other forms of immunotherapy

Superficial bladder cancer: part 2. Management

In the second section of a two-part article, the recent literature is reviewed and the management of nonmuscle-invasive transitional cell carcinoma of the bladder is discussed. Particular attention is given to the indications and timing of intravesical chemotherapy and immunotherapy and the differences in efficacy and side-effect profiles of the available agents. The indications and role of second-look transurethral resection are reviewed. Additionally, the role of bacillus Calmette-Guerin in the management of this disease in terms of definitive treatment and maintenance therapy is discussed. We also offer a review of the literature regarding therapies for bacillus Calmette-Guerin-refractory nonmuscle-invasive transitional cell carcinoma of the bladder and their current place in practice.

Bladder Cancer Immunotherapy: BCG and Beyond

Mycobacterium bovis bacillus Calmette-Guérin (BCG) has become the predominant conservative treatment for nonmuscle invasive bladder cancer. Its mechanism of action continues to be defined but has been shown to involve a T helper type 1 (Th1) immunomodulatory response. While BCG treatment is the current standard of care, a significant proportion of patients fails or do not tolerate treatment. Therefore, many efforts have been made to identify other intravesical and immunomodulating therapeutics to use alone or in conjunction with BCG. This paper reviews the progress of basic science and clinical experience with several immunotherapeutic agents including IFN-α, IL-2, IL-12, and IL-10.

Keyhole limpet hemocyanin potentiates standard immunotherapy for melanoma

INTRODUCTION

Our hypothesis was that keyhole limpet hemocyanin (KLH) would augment the effects of standard immunotherapies for melanoma including interferon-alpha (AIFN) and interleukin (IL)-2.

METHODS

The HTB68 melanoma cell line was treated with KLH, AIFN, and IL-2 as single and combined agents. Cell viability, apoptotic activity, and vascular endothelial growth factor levels were all evaluated.

RESULTS

Cell growth was reduced with KLH (28%), AIFN (54%), and IL-2 (29%) (all P < .001). KLH and IL-2 combined exhibited a 47% inhibition of cell growth, whereas KLH and AIFN combined yielded a 67% reduction in cell growth (both P < .001). KLH and AIFN combined significantly increased both early (10%) and late (14%) apoptotic activity compared with controls (5% and 7%, P < .001).

CONCLUSIONS

The additive effects exhibited by the combination of KLH with AIFN or IL-2 are encouraging and support combination therapy as an effective treatment for this aggressive disease.

Inhibition of melanoma growth by hemocyanin occurs via early apoptotic pathways

BACKGROUND

We hypothesized that keyhole limpet hemocyanin (KLH) would reduce cellular proliferation and effect apoptosis of melanoma cell lines in vitro.

METHODS

Two human melanoma cell lines (HTB68 and HTB72) were subjected to a dose-response treatment regimen of KLH (0.4 microg to 100 microg/well). Cell viability was tested by MTT assay (SIGMA, St Louis, MO) at 72 hours. Apoptosis and necrosis were measured by the Annexin V FITC assay (Biovision Inc, Mountain View, CA).

RESULTS

Melanoma cell proliferation was significantly reduced in the HTB68 cell line treated with 6.3 microg or higher doses of KLH. A significant reduction in cell growth was also observed in the HTB72 cells at 50 and 100 microg of KLH. KLH increased early apoptotic activity, whereas both late apoptosis and necrosis were decreased by the addition of KLH.

CONCLUSIONS

KLH significantly reduces cellular proliferation in vitro in melanoma, via early apoptotic pathways. The results warrant in vivo studies into the effects of KLH in melanoma.

Keyhole limpet hemocyanin, a novel immune stimulant with promising anticancer activity in Barrett's esophageal adenocarcinoma

BACKGROUND

Keyhole limpet hemocyanin (KLH) is a recently described immune stimulant and hapten carrier derived from a circulating glycoprotein of the marine mollusk Megathura crenulata. We previously reported that KLH has significant antiproliferative effects in vitro against breast, pancreas, and prostate cancers. We hypothesized that KLH would be effective against Barrett's esophageal adenocarcinoma in an in vitro model.

METHODS

Barrett's esophageal adenocarcinoma cell lines (SEG-1 and BIC-1) were cultured using standard techniques. Cells were plated at 1 x 10(5) and KLH was added at concentrations ranging from 400 ng to 100 microg/well. After 24 and 72 h incubation, cells were assayed for viability using the MTT technique. Statistical analysis was performed using ANOVA. Apoptosis was evaluated using a cell death detection kit after 16 hours of incubation with KLH.

RESULTS

KLH treatment significantly (p < 0.001) reduced viability in a dose and time-dependent manner. Apoptosis was increased in treated SEG-1 cells, but no changes in apoptosis were seen in treated BIC-1 cells.

CONCLUSIONS

KLH directly inhibits the growth of human Barrett's esophageal cancer in vitro by apoptotic and nonapoptotic mechanisms.

Comparison of viral vectors: gene transfer efficiency and tissue specificity in a bladder cancer model

PURPOSE

Gene transfer efficiency and specific cell targeting of vectors is a major obstacle in preclinical studies of gene therapy for malignant disease. Previous attempts at gene transfer in bladder cancer models have resulted in variable urothelial and tumor transgene expression after intravesical administration of recombinant viral vectors. In the current study we compared the gene transfer efficiencies of different viral vectors.

MATERIALS AND METHODS

We compared the gene transfer efficiencies of the viral vectors replication-deficient adenovirus, attenuated vaccinia virus (NYVAC) and canarypox virus (ALVAC) in vitro and in an orthotopic murine bladder cancer model. We used beta-galactosidase and firefly luciferase reporter gene expression to compare gene transfer efficiency.

RESULTS

Significantly higher transgene expression was observed in vitro when these cells were infected with NYVAC or ALVAC compared with adenovirus vectors. Similarly the efficiency of adenovirus vectors to transfer genetic material into bladder urothelium and orthotopic bladder tumors was inferior to that of ALVAC and NYVAC vectors, which interestingly appeared to have a predilection to infect the orthotopic tumor. Analysis of the expression of coxsackie-adenovirus receptor using reverse transcriptase-polymerase chain reaction revealed the bladder tumor cell lines were lacking this adenovirus receptor. While adenovirus transferred genes poorly to normal bladder, coxsackie-adenovirus receptor expression was high in bladder tissue.

CONCLUSIONS

The viral vectors examined in these experiments resulted in significantly different gene transfer in the orthotopic bladder cancer model, underscoring the importance of vector selection in gene therapy protocols.

In vitro anticancer effects of a novel immunostimulant: keyhole limpet hemocyanin

BACKGROUND

Keyhole limpet hemocyanin (KLH) is a recently described immune stimulant and hapten carrier derived from a circulating glycoprotein of the marine mollusk Megathura crenulata. It has been reported to be a potent form of intravesical immunotherapy for the treatment of transitional cell carcinoma of the bladder and has been used in a variety of genitourinary tumors. We hypothesized that KLH would be effective against other cancer cells in vitro.

METHODS

Multiple cancer cell lines were tested, including estrogen-dependent breast (MCF-7), estrogen-independent breast (ZR75-1), pancreas (PANC-1, MIA-PaCa), and prostate (DU145). Serial twofold dilutions of KLH were prepared in sterile 96-well plates. Dose-response curves were performed beginning with a concentration of 100 microg of KLH/well and ending at a concentration of 0.8 ng/well. Cells were added at concentrations of 5 x 10(4) cells per well. Cell viability was evaluated at 24 and 72 h by MTT assay at an absorbance of 570 nm.

RESULTS

Significant (P < 0.05) cancer cell growth inhibition was observed in four of the five cell lines tested at both time treatment intervals. The breast cancer line ZR75-1 exhibited a mean growth inhibition of 43 +/- 1.1% (range 37 to 59%) at 72 h, whereas treated MCF-7 cells had an average of 39 +/- 9.1% growth inhibition (range 35 to 44%) at these same concentrations. Treated PANC-1 cells had a mean growth inhibition of 19 +/- 0.8% (range 4 to 46%) at 72 h. The DU145 prostate cancer cell line averaged a 6 +/- 1.3% growth inhibition (range -19 to 55%) over the concentrations tested.

CONCLUSIONS

The direct growth inhibition of multiple tumor cell-lines exhibited by KLH is significant and warrants further in vitro mechanistic studies and in vivo experiments. Investigation into the efficacy and mechanism of response could directly lead to more effective treatment regimens for patients suffering from these diseases.

Immunotherapy for bladder cancer

The primary role of immunotherapy for bladder cancer is to treat superficial transitional cell carcinomas (ie, carcinoma in situ, Ta, and T1). Immunotherapy in the form of bacille Calmette-Guérin (BCG), interferon, bropirimine, keyhole limpet hemocyanin, and gene therapy is intended to treat existing or residual tumor, to prevent recurrence of tumor, to prevent progression of disease, and to prolong survival of patients. Presently, BCG is commonly used and is the most effective immunotherapeutic agent against superficial transitional cell carcinoma. Data support that BCG has a positive impact on tumor recurrence, disease progression, and survival. Proper attention to maintenance schedules, route of administration, dosing, strains, and viability is essential to obtain the maximum benefits of BCG immunotherapy. This review highlights and summarizes the recent advances concerning immunotherapy, with special emphasis on BCG therapy for transitional cell carcinoma.

Interferons and bladder cancer

With the introduction of BCG, intravesical instillation of immunotherapeutic agents has become a mainstay of therapy in the treatment of superficial bladder cancer. Interferon is capable of inducing a non-specific cellular and humoral immune response towards tumor cells. It has shown promise in reducing the recurrence and progression rates of superficial bladder cancer. In contrast to BCG, intravesical interferon is associated with minimal side effects and a very low dropout rate. Current research has focused on the use of interferon in combination with immunotherapeutic and cytotoxic drugs.

Antitumour immunity of Bacillus Calmette-Guerin and interferon alpha in murine bladder cancer

Intravesical Bacillus Calmette-Guerin (BCG) immunotherapy is currently the optimal choice for aggressive superficial bladder cancer, with a 70% response rate. This study investigated whether the antitumour response elicited by BCG could be improved by the addition of recombinant interferon alpha (IFN alpha) in the subcutaneous murine MB49 bladder tumour model. The combination of BCG and IFN alpha had superior and earlier antitumour activity than BCG alone for MB49 cells in culture. A total of 14/15 BCG plus interferon-treated mice and 8/16 BCG-treated mice became tumour free after treatment. BCG or the combination treatment significantly raised the T-helper 1 (Th1) cytokine IFN gamma levels compared with levels in all other groups. Whilst BCG therapy alone increased CD4+ and CD8+ populations in spleens, the combination of BCG and IFN alpha also increased alpha beta+ T cells significantly. Our results suggest that the combination of BCG and IFN alpha may represent a more efficacious therapeutic than BCG alone for superficial bladder cancer.

IFN-α 2B Enhances Th1 Cytokine Responses in Bladder Cancer Patients Receiving Mycobacterium bovis Bacillus Calmette-Guérin Immunotherapy

Combination therapy with intravesical bacillus Calmette-Guérin (BCG) plus IFN-α for superficial bladder cancer has been demonstrated to be more effective than either single agent alone in animal studies and of suggested greater efficacy in clinical studies. However, the mechanism by which IFN-α enhances BCG-mediated antitumor activity is poorly understood. Using PBMCs from bladder cancer patients, IFN-α was found to substantially enhance the efficacy of BCG to induce IFN-γ production. Among 34 patients tested, 80% showed &gt;4-fold increase. This effect of IFN-α was observed in both initial and memory responses to BCG. In addition, IFN-α up-regulated BCG-induced IL-12 and TNF-α and down-regulated BCG-induced IL-10. Neutralizing endogenous IL-10 or adding exogenous IL-12 provided further synergy for IFN-γ production. In clinical practice, intravesical IFN-α 2B (50 million units (MU)/dose) was observed to accelerate urinary IFN-γ production to low-dose BCG (one-tenth or one-third of a full dose) in patients treated with combination therapy compared with BCG alone. These results suggest that IFN-α is a potent BCG enhancer that polarizes the BCG-induced immune response toward the cellular immune pathway by promoting Th1 cytokine expression and reducing Th2 cytokine expression. This study provides an immunological basis for future rational use of IFN-α in conjunction with intravesical BCG for bladder cancer immunotherapy.

Superficial bladder cancer: the role of interferon-alpha

PURPOSE

We evaluate the clinical experience with recombinant interferon-alpha in superficial transitional cell carcinoma and discuss the most rational use of recombinant interferon-alpha in the context of current treatment options.

MATERIALS AND METHODS

The available data were reviewed and discussed at a consensus conference in August 1996. The conclusions and recommendations are those of the authors based on the consensus reached at that meeting.

RESULTS

While bacillus Calmette-Guerin (BCG) is recognized as the most efficacious intravesical agent in the prophylaxis and treatment of superficial transitional cell carcinoma, it is associated with significant toxicities and a 20 to 40% relapse rate. Interferons, particularly recombinant interferon-alpha, have demonstrated efficacy against primary and recurrent papillary transitional cell carcinoma and carcinoma in situ with minimal toxicity, although the response and relapse rates are inferior to BCG. Intravesical recombinant interferon-alpha therapy has also produced responses in patients who failed to respond or were refractory to BCG or chemotherapy.

CONCLUSIONS

The clinical experience suggests that recombinant interferon-alpha has an important role in the treatment of superficial transitional cell carcinoma, particularly as second line therapy following failure of BCG or chemotherapy, and it may have synergistic effects when combined with chemotherapy or BCG. We propose a prospective randomized study comparing the efficacy of recombinant interferon-alpha, BCG and BCG plus recombinant interferon-alpha as maintenance following complete response to primary BCG therapy. The proposed study would also investigate the efficacy of BCG plus recombinant interferon-alpha as second line therapy following BCG failure. This study will be important to determine the most effective strategy to integrate recombinant interferon-alpha into current treatment options for superficial bladder cancer.

Pharmacological biocompatibility between intravesical preparations of BCG and interferon-alpha 2B

PURPOSE

To determine if BCG and interferon alpha-2B are mutually compatible as mixed intravesical agents for clinical bladder cancer therapy.

MATERIALS AND METHODS

Mutual compatibility was assessed by measuring IFN-alpha's effect on BCG metabolic activity, growth rate, and clumping tendency and conversely by observing BCG's effect on IFN-alpha's anti-viral activity. Optical density at 600 nm. (OD600) was used to estimate the number of colony forming units of BCG in suspension during 3 hours measurements of clumping and 8 days measurements of BCG proliferation. BCG viability was evaluated using a substrate marker, MTT, which correlates with BCG density and metabolic activity. The anti-viral activity of IFN-alpha was determined in a cytopathic protection bioassay using the encephalomyocarditis virus/FS-4 cell system.

RESULTS

Continuous shaking of reconstituted BCG for 3 hours at 37C resulted in a marginal (11.3%) drop in OD600 which was minimally altered by inclusion of IFN-alpha at 2 million units (MU)/ml. (12.7% drop). Metabolic activity and growth rate of BCG alone or BCG with IFN-alpha were essentially identical. IFN-alpha's antiviral activity was not affected by incubation with BCG.

CONCLUSIONS

The inclusion of IFN-alpha into the usual BCG formulation for intravesical administration has no apparent effect on BCG's viability or tendency to form clumps in suspension. Similarly, the physical mixing of IFN-alpha with BCG does not impair its biological activity. Thus, both agents are pharmacologically compatible for future clinical studies involving combination intravesical therapy.

Cytotoxic effects of alpha- and gamma-interferon and tumor necrosis factor in human bladder tumor cell lines

We investigated the activity of alpha-interferon (alpha-IFN), gamma-interferon (gamma-IFN) and tumor necrosis factor-alpha (TNF-alpha) in a panel of ten human bladder tumor cell lines. All cytokines were tested at concentrations of 100-10,000 U/ml in a clonogenic assay system. We found that alpha-IFN was active against five of the ten lines while gamma-IFN was only active against one line. TNF was active against five of the ten lines. Maximum synergisms were obtained between the alpha-IFN and TNF, occurring in nine of the ten cell lines. We conclude that alpha-IFN and TNF are active as single agents and synergistic when used together in vitro in human bladder tumor cell lines.